In 2001, Lexi and Sydney were born conjoined twins. Now, they’re about to separate for good.

On March 9 2001 Lexi and Sydney Stark were born conjoined at the spine in Colorado. Seven months later, the pair underwent life-threatening separation surgery, and against all odds, they survived.

Now sixteen years after their surgical separation, the family is sharing their story.

The twins’ parents, Emily and James Stark, knew that their daughters were going to be conjoined prior to the birth, they shared on Monday’s episode of Megyn Kelly Today.

A doctor recognised something unusual in an ultrasound, and unfamiliar with the condition, brought out a 1000 page medical book, in which there were two small paragraphs on conjoined twins.

The twins in the womb. Image: Megyn Kelly Today.

"[The doctor] looked at us and said 'they're joined somewhere in the lower region'," shared Emily Stark, adding that when she heard the news she tuned out and stared at the ceiling, allowing her husband to take over.